Merge "Atrace:use ReadFileToString to read file" am: 3cebac7 am: ab682e4
am: 2ea63d8

* commit '2ea63d8c861abf88d886358ced72a32ca782f62f':
  Atrace:use ReadFileToString to read file

Change-Id: I80193bc32079916c069ac16f95d8397b7c666eed